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Additional measurements (organic soluble N and denitrification) from integrated N grassland farmlets - NT1801

Models for describing and predicting N cycling within grassland farming systems are as yet unable to account for all the annual N inputs. It is essential that this information is provided in order to be certain that changes in management designed to increase N use efficiency are effective, and do not promote a transfer of the problem. The overall aim of this study will be to provide additional information (on organic N losses through drainage and intensive denitrification measurements over 3 defined drainage periods) to help complete N balances for the ongoing integrated N management experimental systems at North Wyke. The study will be composed of 2 specific objectives outlined as follows, together with ways in which they might be achieved: 1. Determination of the extent of transfer of mobile organic N in drainage water below the rooting zone and in surface run-off from grassland soils. Annual estimates will be made of N leached in organic forms from a range of grassland management systems on the North Wyke experimental farmlets throughout a number of drainage periods. Effects of 3 different grassland management systems on organic N flow in waters, and effects of cutting, grazing and farm waste returns on the extent of organic N loss in a freely draining soil will also be determined; 2. Provision of a more robust annual estimate of denitrification in grassland soils under different managements. Assessments of denitrification losses from the farmlets will be provided on at least a weekly basis, and any differences in denitrification in areas affected by cutting, grazing and farm waste returns will be determined. The impact of specific fertilizer events on denitrification over time will be monitored. Improvements will be made to model definitions of amounts being lost through denitrification from different components of grassland production and the controls over this process. Results of the study will allow a much more complete quantification of N flows and losses in grassland systems.
Time-Scale and Cost
From: 1995

To: 1998

Cost: £133,760
Contractor / Funded Organisations
Institute of Grassland and Environment Research (IGER)
Fields of Study
Fertilisers and Nitrate Pollution